Combustible Mixed Butanol Fuels

ABSTRACT

A fuel composition including mixed butanols, such as for example, 2-butanol, iso-butanol and tert-butanol, preferably 2-butanol and tert-butanol is provided. Methods of preparing and using the mixed butanols composition as combustible neat fuels and/or oxygenate fuel constituents in gasoline, diesel, jet fuel, aviation gasoline, heating oil, bunker oil, and the like are also provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/222,374, filed on Jul. 1, 2009, which hereby is incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a fuel component and composition and an octane enhancer, including the method of creating the same.

2. Description of the Related Art

Internal combustion engines are commonly used on mobile platforms, in remote areas or in lawn and garden tools. There are various types of internal combustion engines. Spark type engines compress volatile fuels, such as gasoline, before ignition. Compression type engines take in air and compress it to generate the heat necessary to ignite the fuel, such as diesel.

When a fuel (gasoline or diesel) is combusted, it produces pollutants in the form of hydrocarbons (HC), sulfuric oxides (SOx), nitrogen oxides (NOx), carbon monoxide (CO) and soot (particulates). In addition, fuels in warm climates tend to evaporate due to the presence of volatile organic compounds (VOCs). Nitrogen oxides and volatile organic components react together in sunlight to form ground level ozone, a component of smog.

Although hydrocarbon fuels are the dominant energy resource, alcohols, especially methanol and ethanol, have been used as fuels. In the 1970s, gasohol, a blend of mostly gasoline with some ethanol, was introduced during the Arab oil embargo. The primary alcohol fuel is ethanol. The ethanol is blended into gasoline in various quantities, normally at 10%, which typically results in a higher octane rating than regular gasoline. E-85 fuel contains 85% ethanol and 15% gasoline and M-85 has 85% methanol and 15% gasoline. Unfortunately, at that time, many of the elastomeric engine seals, hoses and gasket components were designed only for gasoline or diesel and deteriorated with the use of ethanol. Furthermore, the engines had to be equipped with fluorinated elastomers to run ethanol-based fuels.

The ethanol is often created through fermentation processes from grain. Bio-fuels often contain mixed alcohols together with other oxygenate compounds.

Further limitations exist with respect to the use of grain-based fuels. For example, grain ethanol is expensive to produce. Furthermore, producing sufficient quantities of grain ethanol to satisfy the needs of the transportation industry is not practical because food crops and feed crops are and have been diverted into fuel. In addition, both methanol and ethanol have relatively low energy contents when compared to gasoline on a volumetric basis. Methanol contains about 50,000 Btu's/gallon and ethanol contains about 76,000 Btu's/gallon while gasoline contains about 113,000 Btu's/gal.

Long chain alcohols are often used together with amines/anilines as inhibitors to prevent metal corrosion and rubber/plastics swellings caused by the ethanol fuels. These long chain alcohols, such as dodecanol, can also be used as emulsifying agents. Mixed low cost methanol, ethanol were used together with long chain alcohols to form alcohol blended diesels or used as emulsifying diesel adjustors. However, long chain alcohols are relatively expensive to produce. The methanol-based and ethanol-based diesel also suffer from the drawback that they need other additives, such as long chain alcohol, alkyl esters and fatty acids to maintain a minimum Cetane number above 40 and to assure the diesel burns efficiently.

Some time ago, lead was added to gasoline to boost its octane rating, thereby improving the antiknock properties of gasoline. Lead is being eliminated in most countries from gasoline for environmental reasons. In response to the need to phase out lead, gasoline sold in the United States and many other countries was blended with up to 15% volumes of methyl-tertiary-butyl-ether (MTBE), an oxygenate, in order to raise the octane rating and to reduce environmentally harmful exhaust emissions.

MTBE is itself a pollutant, having an objectionable and strong odor and taste and having been classified as a potential human carcinogen. MTBE leakage from underground storage tanks has created a demand for an alternative product, particularly as MTBE is soluble in water (42 g/L @ 25° C.) and is low in biodegradability thereby polluting ground water. Several U.S. states, including California, are phasing out the use of MTBE.

The industry is replacing MTBE with the use of fermented grain ethanol, but as discussed above, producing the necessary quantities of grain ethanol to replace MTBE is problematic in specific regions.

MMT, Methylcyclopentadienyl Manganese Tricarbonyl, has been a controversial gasoline additive for many years. MMT is able to increase octane but it increases emissions, which may have an adverse effect on health and exhaust catalytic conversion systems.

There is a need for an additive or fuel that has improved octane rating as compared to gasoline and increased efficiency of combustion. There is a need for a fuel that reduces harmful emissions and airborne soot when combusted, either in neat form or as a fuel constituent.

There is also a need to provide a fuel of similar octane and BTU value to gasoline but without the use of tetraethyllead, MTBE, methanol, ethanol, or MMT. It would also be desirable to provide a fuel additive that lowers the Reid Vapor Pressure of the fuel at least as well as, but without the use of, MTBE.

SUMMARY OF THE INVENTION

In view of the foregoing, fuel additives and fuel compositions are provided as embodiments of the present invention. As an embodiment of the present invention, a fuel composition that is environmentally friendly and has comparable performance properties to ethanol-based or MTBE-based fuels is provided. In this embodiment, the fuel composition includes a fuel component and a fuel additive. In an aspect, the fuel composition consists essentially of a fuel component and a fuel additive. The fuel component being present in an amount sufficient to provide adequate BTU content for use in combustion or compression engines. The fuel additive includes at least two isomers of butanols and is present in an amount sufficient to improve an octane rating for the fuel composition.

As another embodiment of the present invention, a neat fuel composition that is environmentally friendly and has comparable performance properties to ethanol-based or MTBE-based fuels in provided. In this embodiment, the neat fuel composition includes a mixed butanol fuel. In an aspect, the neat fuel composition consists essentially of a mixed butanol fuel.

The current invention includes compositions of at least two of 2-butanol, iso-butanol or tert-butanol, in combination with or as a fuel for use in combustion or compression engines. In a preferred embodiment, 2-butanol, iso-butanol and tert-butanol are used. The at least two or more of 2-butanol, iso-butanol or tert-butanol are referred to as “mixed butanols” hereafter. Mixed butanols are useful as a combustible neat fuel or as an oxygenate fuel constituent in gasoline, diesel, jet fuel, aviation gasoline, heating oil, bunker oil or other similarly hydrocarbon based fuel stock to create a butanol enhanced fuel. The combustible neat fuel and the butanol enhanced fuel demonstrate numerous benefits in comparison to gasoline, diesel, jet fuel, aviation gasoline, heating oil, bunker oil or other similarly hydrocarbon based fuels without the mixed butanols. These benefits include increased demonstrated combustion efficiency, reduced emissions of harmful gases and particulate matter. Also, the butanol enhanced fuel and the combustible neat fuel show improved BTU content on a volumetric basis when compared to similar fuels containing substantial amounts of methanol or ethanol. In addition to these benefits, mixed butanols act as an octane enhancer as a replacement to tetra-ethyl-lead, MTBE, methanol, ethanol, MMT and other octane boosters. Mixed butanols do not suffer from the drawbacks associated with these other octane boosters. In the case of the butanol enhanced fuel, mixed butanols demonstrate low and stable Reid vapor pressure blending characteristics. Given the reduced corrosiveness of mixed butanols as compared to methanol/ethanol, the combustible neat fuel or the butanol enhanced fuel can be safely stored in existing storage and transportation facilities and can be used in modern engines without engine modifications. An added benefit is the low toxicity of the mixed butanols and the relative biodegradability which makes the mixed butanols a clear choice for environmental reasons to replace other octane boosters.

Butanol isomers, due to their different structures, have somewhat different physical properties. Isobutanol, 2-butanol, and n-butanol have only limited solubility in water, as contrasted to methanol, ethanol, and propanol, which are fully miscible with water. Therefore, the mixed butanol of the current invention provides environmental advantages over the use of C1-C3 alcohols. 2-butanol is particularly preferred as a predominant portion of the mixed butanols.

Butanols of the current invention can be derived from various sources, including reaction to derive butanols from fossil fuels or through fermentation of biomass from bacteria.

The current invention encompasses any combination of butanol isomers to create the mixed butanols. One preferred embodiment includes the mixed butanols being 5-95 volume % 2-butanol and 5-95 volume % tert-butanol; or alternatively, being 40-60 volume % 2-butanol and 40-60 volume % tert-butanol. This mixed butanol is preferably 1-60 vol % of the butanol enhanced fuel. The presence of any substantial amounts of methanol, ethanol, and propanol in the combustible neat fuel and the butanol enhanced fuel is also possible.

In the current invention, there is an absence of substantial amounts of long chain alcohols. Long chain alcohols, such as octanol and higher, are also absent. The mixed butanols are effective to raise octane rate in the absence of dodecanol, a commonly used octane booster, or other expensive oxygenates.

As indicated previously, the mixed butanols used in embodiments of the present invention can include a variety of butanols. In an aspect, the mixed butanols includes n-butanol or bio-butanol. In an aspect, the mixed butanols excludes n-butanol or bio-butanol.

In embodiments of the present invention, the fuel compositions described herein exclude the use of tetraethyllead, MTBE, methanol, ethanol, or MMT.

The fuel compositions of the present invention have physical properties that are comparable to fuel compositions containing alcohol-based, such as ethanol-based, octane enhancers, but without many of the disadvantages associated with such fuel compositions. The physical properties that are important to fuel compositions include RON values, BTU values, RVP values, MON values, cetane index values, heat of combustion, cloud point values, pour point values, smoke point values, and the like. In an aspect, the fuel compositions of the present invention exclude the use of non-butanol alcohols. For example, the fuel compositions of the present invention exclude the use of methanol, ethanol, or propanol. However, these alcohols can be blended with the mixed butanol based fuels at any ratios.

The mixed butanols are an effective replacement for tetra-ethyl-lead, MTBE and MMT. In a preferred embodiment, there is an absence of MTBE and tetra-ethyl-lead. While MMT is still used in some fuel blends in the world, a preferred embodiment of the current invention includes an absence of MMT.

Similar to the lower alcohols, lower ketones (such as acetone) are highly water soluble. The current invention is practiced substantially in the absence of such lower ketones. Another advantage of the invention and the exclusion of the use of methanol and ethanol is the ability to also exclude long chain alkyl esters and fatty acids that are often used with methanol/ethanol to maintain a minimum Cetane number of about 40 and to assure that diesel burns efficiently.

Due to the beneficial Reid vapor pressure of the mixed butanols, the glycerol ether often added to methanol/ethanol fuels to reduce vapor pressure can be eliminated as well.

DETAILED DESCRIPTION

As an embodiment of the present invention, a fuel composition that is environmentally friendly and has comparable performance properties to MTBE and/or ethanol-based fuels is provided. In this embodiment, the fuel composition includes a fuel component and a fuel additive. The fuel component being present in an amount sufficient to provide adequate BTU content for use in combustion or compression engines. The fuel additive includes a butanol and is present in an amount sufficient to improve an octane rating for the fuel composition. In an aspect, the butanol consists essentially of 2-butanol and tert-butanol, or combinations thereof. In an aspect, the butanol excludes n-butanol.

In an aspect, the butanol included in the fuel additive includes n-butanol. In another aspect, the butanol includes 2-butanol, iso-butanol, tert-butanol, or combinations thereof. In an embodiment of the present invention, the butanol includes 2-butanol and tert-butanol. The 2-butanol is present in a range of about 5 vol. % to about 95 vol. % and the tert-butanol is present in a range of about 5 vol. % to about 95 vol. %. The 2-butanol is present in a range of about 40 vol. % to about 60 vol. % and the tert-butanol is present in a range of about 40 vol. % to about 60 vol. %. Other suitable types of mixed butanols and amounts of butanols will be apparent to those of skill in the art and are to be considered within the scope of the present invention.

The fuel compositions of the present invention have physical properties that are comparable to fuel compositions containing ethanol-based, or MTBE based, octane enhancers, but without many of the disadvantages associated with such fuel compositions. The physical properties that are important to fuel compositions include RON values, BTU values, RVP values, MON values, cetane index values, heat of combustion, cloud point values, pour point values, smoke point values, and the like. In an aspect, the fuel compositions of the present invention exclude the use of non-butanol alcohols. For example, the fuel compositions of the present invention exclude the use of methanol, ethanol, or propanol. However, the addition of other alcohols at any ratios into mixed butanol based fuel will be apparent to those of skill in the art and are to be considered within the scope of the present invention.

In embodiments of the present invention, the fuel compositions described herein exclude the use of tetraethyllead, MTBE, methanol, ethanol, or MMT.

Octane Measurement Methods

The octane number does not correspond to the concentration of any one constituent in the fuel, but rather to the pre-ignition properties of the fuel as compared with standard fuel mixtures. The octane rating is a measure of the autoignition resistance of gasoline (petrol) and other fuels used in spark-ignition internal combustion engines. Octane is measured relative to a mixture of isooctane (2,2,4-trimethylpentane, an isomer of octane) and n-heptane. For example, an 87-octane gasoline has the same knock resistance as a mixture of 87 vol-% isooctane and 13 vol-% n-heptane. However, this does not mean that the gasoline actually should contain these chemicals in these proportions—merely that the gasoline has the same autoignition resistance as the described mixture. A high tendency to autoignite, or low octane rating, is undesirable in a gasoline engine (but desirable in a diesel engine).

The most common type of octane rating worldwide is the Research Octane Number (RON). RON is determined by running the fuel through a specific test engine with a variable compression ratio under controlled conditions, and comparing these results with those for mixtures of isooctane and n-heptane. In most countries the “headline” octane that is shown on the pump is the RON.

Effects of Octane Rating

Higher octane ratings correlate to higher activation energies. Activation energy is the amount of energy necessary to start a chemical reaction. Since higher octane fuels have higher activation energies, it is less likely that a given compression will cause knocking. Knocking can damage an engine. Lower-octane gas (e.g., 87-octane gasoline) can handle the least amount of compression before igniting.

Compression is directly related to power (see engine tuning), so engines that require higher octane usually deliver more power. Engine power is a function of the fuel as well as the engine design and is related to octane ratings of the fuel. Power is limited by the maximum amount of fuel-air mixture that can be forced into the combustion chamber. At partial load, only a small fraction of the total available power is produced because the manifold is operating at pressures far below atmospheric. In this case, the octane requirement is far lower than what is available. It is only when the throttle is opened fully and the manifold pressure approaches to atmospheric (or higher in the case of supercharged or turbocharged engines) that the full octane requirement is achieved.

Many high-performance engines are designed to operate with a high maximum compression and thus need a high quality (high energy) fuel usually associated with high octane numbers and thus demand high-octane premium gasoline.

Engines perform best when using fuel with the octane rating they were designed for. There can possibly be a minimal increase in performance by using a fuel with a different octane rating.

As indicated previously, the most common type of octane rating is the Research Octane Number (RON). RON is determined by running a fuel in a test engine with a variable compression ratio under controlled conditions, and comparing the results with those for mixtures of iso-octane and n-heptane. In an aspect, the fuel compositions of the present invention have RON values ranging from between about 85 and to about 110.

In an aspect, the fuel compositions of the present invention have BTU values are ranging from between about 105,000 BTU/gallon and to about 120,000 BTU/gallon.

In an aspect, the fuel compositions of the present invention have a RVP ranging from about 0.2 psi to about 20 psi.

Another type of octane rating, called Motor Octane Number (MON), or the aviation lean octane rating, is generally a better measure of how fuel behaves when under load as it is done at 900 rpm instead of the 600 rpm of the RON. MON testing typically uses a similar test engine to that used in RON testing, but with a preheated fuel mixture, a higher engine speed, and variable ignition timing to further stress the fuel's knock resistance. Depending on the composition of the fuel, the MON of a modern gasoline will be about 8 to 10 points lower than the RON. Normally, fuel specifications require both a minimum RON and a minimum MON. In an aspect, the fuel compositions of the present invention have MON values ranging from about 75 to about 100.

Cetane number or CN is a measurement of the combustion quality of diesel fuel during compression ignition. Cetane number is a measure of a fuel's ignition delay; the time period between the start of injection and start of combustion (ignition) of the fuel. In a particular diesel engine, higher cetane fuels will generally have shorter ignition delay periods than lower cetane fuels. In an aspect, the fuel compositions of the present invention have cetane index values ranging from about 48 to about 55.

Another property that is important in the analysis of fuels is the energy content of the fuel. The energy content (also referred to as heating value) of diesel fuel is its heat of combustion; the heat released when a known quantity of fuel is burned under specific conditions. In an aspect, the fuel compositions of the present invention have heat of combustion values ranging from about 118,000 BTU/gal to about 130,000 BTU/gal.

The cloud point of a fuel is the temperature at which dissolved paraffin is no longer completely soluble, precipitating as a second phase giving the fuel a cloudy appearance. In an aspect, the fuel compositions of the present invention have cloud point values ranging from about −40° C. to about 5° C.; or alternatively, ranging from about 4.5° C. to about 5.75° C.

Another property that is considered when deciding upon a fuel to use is the fuel's pour point. The fuel's pour point is a temperature below the fuel's cloud point. Fuel stops flowing below the pour point. In an aspect, the fuel compositions of the present invention have pour point values ranging from about 5-12° C. below the cloud point.

Yet another property that is considered when deciding upon a fuel to use is the fuel's smoke point value. In an aspect, the fuel compositions of the present invention have smoke point values ranging from about 10 mm to about 25 mm. Smoke point is defined as the flame height immediately prior to the flame emitting smoke. Smoke point has been recognized as a measure of a fuel to form soot and has been used to judge the quality of various liquid fuels.

In embodiments of the present invention, the fuel composition includes a fuel component. In an aspect, the fuel component includes gasoline, diesel, jet fuel, aviation gasoline, heating oil, bunker oil, or combinations thereof. Other types of fuels can be used in embodiments of the present invention will be apparent to those of skill in the art and are to be considered within the scope of the present invention.

In an aspect, the fuel component is present in a range of about 40 vol. % to about 99 vol. % and the fuel additive is present in a range of about 1 vol. % to about 60 vol. %; or alternatively, the fuel component is present in a range of about 80 vol. % to about 99 vol. % and the fuel additive is present in a range of about 1 vol. % to about 20 vol. %. The amounts of each component can vary depending upon the desired physical properties of the resulting fuel composition. Other suitable amounts of each component will be apparent to those of skill in the art and are to be considered within the scope of the present invention.

As another embodiment of the present invention, a neat fuel composition that is environmentally friendly and has comparable performance properties to alcohol based fuels in provided. In this embodiment, the neat fuel composition comprises a mixed butanol fuel. In an embodiment, the mixed butanol fuel includes 2-butanol, iso-butanol, tert-butanol, or combinations thereof. In an embodiment, the mixed butanol fuel consisting essentially of only 2-butanol, iso-butanol, tert-butanol, or combinations thereof. In an aspect, the mixed butanol fuel excludes n-butanol.

Besides the compositional embodiments described herein, a method of preparing a fuel composition for use in combustion or compression engines is also provided. In this embodiment, a mixed butanol composition is combined with a fuel component. The mixed butanol composition includes 2-butanol, iso-butanol, tert-butanol, or combinations thereof and is present in an amount sufficient to improve an octane rating for the fuel composition. The fuel component includes gasoline, diesel, jet fuel, aviation gasoline, heating oil, bunker oil, or combinations thereof. The fuel component is present in an amount sufficient to provide adequate BTU content for use in combustion or compression engines. As with other embodiments of the present invention, the fuel component is present in a range of about 40 vol. % to about 99 vol. % and the fuel additive is present in a range of about 1 vol. % to about 60 vol. %; or alternatively, in a range of about 80 vol. % to about 99 vol. % and the fuel additive is present in a range of about 1 vol. % to about 20 vol. %.

In another embodiment, the composition's RON values are between 85 and 110; or alternatively, between 67.4 and 101.1. In another embodiment, the composition's BTU values are between 105,000 BTU/gallon and 120,000 BTU/gallon.

As another embodiment of the present invention, a method of using a mixed butanols composition as combustible neat fuels and/or oxygenate fuel constituents in gasoline, diesel, jet fuel, aviation gasoline, heating oil, bunker oil, or combinations thereof is provided. As with other embodiments of the present invention, the mixed butanols composition is comprised of at least two of n-butanol, 2-butanol, iso-butanol and Cert-butanol, preferably 2-butanol, iso-butanol, and tert-butanol. In an embodiment, the mixed butanol fuel includes 2-butanol, iso-butanol, tert-butanol, or combinations thereof. In an aspect, the mixed butanols composition consisting essentially of only 2-butanol, iso-butanol, tert-butanol, or combinations thereof. In an aspect, the mixed butanols composition excludes n-butanol.

As indicated previously, the current invention creates an advantage due to the high value of BTU/gallon of the mixed butanols. Methanol contains about 57,250 Btu's/gallon and ethanol contains about 76,330 Btu's/gallon while gasoline contains about 116,100 Btu's/gal. The mixed butanols are closer to the Btu/gallon value of gasoline.

Table 1 includes a list of the test methods used to test the fuels made in accordance with embodiments of the present invention. The test results are shown in Table 2.

TABLE 1 Test methods Test method Physical property ASTM D-2699 RON ASTM D-2700 MON ASTM D-323(gasoline) RVP ASTM D-5191 (diesel) ASTM D-4052/ASTM D-5291 Specific Gravity ASTM D-976 Cetane Number ASTM D D-5773 Cloud Point ASTM D D-97 Pour Point ASTM D D-1322 Smoke Point ASTM D-4840 (diesel) BTU (Heat of Combustion) ASTM D04809 (gasoline)

In a first test run, the gasoline components, pentane, reformates and light straight run naphtha, and diesel were obtained from a Saudi Aramco refinery without any other additives. Each of the gasoline components were tested individually. The ratios of each component are listed in Table 2. Butanols were purchased directly from the chemical supply market and used without any purification. The mixed butanols-diesel fuel blend containing 10% mixed butanols and 90% diesel fuel was tested.

Based on the test results, a gasoline with 21.6% of pentane, 64.7% of reformates and 13.7% of LSRN was used as standard gasoline. The two samples, one with MTBE and another with 1-butanol, at the same oxygen content level (O %=2.8) were compared and tests results are shown in Table 3. Then a gasoline with 45% LSRN and 55% reformate was used as standard gasoline to test the behaviors of butanols (single butanol or mixed butanols) at the same volume (15%). The ratios of components and tests results are listed in Table 4.

Diesel used for the experiments was obtained from one Aramco refinery without any other additives. Diesel and butanols were blended as listed in Table 5 which contains 10% butanols and 90% diesel fuel. The test results are listed in Table 6.

TABLE 2 Gasoline Composition 1 (V %) Sample No. C5 Reformate LSRN MTBE n-butanol 1 100 0 0 0 0 2 0 100 0 0 0 3 0 0 100 0 0 4 0 0 0 100 0 5 0 0 0 0 100 6 21.6 64.7 13.7 0 0 7* 76 0 24 8* 69 31 0 *7-8 used sample 6 as standard gasoline

TABLE 3 Test Results of Gasoline-1-butanols Heat of Combustion Sample No. Specific Gravity RVP (psi) RON (BTU/lb) 1 0.6255 18.1 78.9 12756 2 0.8121 4.73 101.1 17908 3 0.6587 11.95 67.4 16398 4 0.7400 8.21 114 13627 5 0.8098 0.36 96 15354 6 0.7554 8.5 92.2 17117 7 0.7593 8.2 92.1 16560 8 0.7561 8.7 96.4 16858

Experiments 6-8 demonstrate that 1-butanol can be blended into gasoline in place of MTBE. The 1-butanol blended gasoline showed similarity to MTBE blended gasoline performance and characteristics in RVP and BTU with lower RON.

TABLE 4 Butanol Effects on Gasoline Heat of Combustion Gasoline Tests RVP (psi) (BTU /lb) MON RON  9 45% LSRN 55% 7.05 16970 81.4 87.7 reformate 10 MTBE 8.21 13627 96 109 11 1-butano1 0.36 15354 83.5 100 12 2-butanol 0.83 15109 92.5 108 13 t-butanol 4.44 14936 — — 14 iso-butanol 0.54 13910 93.6 111 15 MTBE 15% 7.41 16280 85.1 92.7 16 1-butanol 15% 6.66 15131 81.5 89 17 2-butanol 15% 6.7 16520 84.1 92.5 18 iso-butanol 15% 6.69 17019 83.4 91.9 19 t-butanol 15% 7.06 16685 83.1 90.9 20 2-butanol/t-butanol 6.98 17514 83.2 91 (1:1) 15%

The tests on pure butanols indicated that both 2-butanol and iso-butanol have similar RON as compared to that of MTBE, with particular note to run 10, 12 and 14. However, the MONs of butanols are lower than that of MTBE. By blending butanols with gasoline, this effect is overcome. This is particularly true with 2-butanol and iso-butanol (runs 15, 16 and 17). At the same time, decrease in RVP and increase in BTU was observed. Butanol blendings are able to enhance the efficiency of the fuel combustions. Of the butanols, 2-butanol, iso-butanol and tert-butanol were particularly effective as providing desirable results. The blending characteristics of the mixed butanols were not linear and are therefore considered unpredictable. Therefore, the blending octane numbers provided by the mixed butanols will depend upon fuel products that are blended volume percentages of the mixed butanols.

TABLE 5 Diesel Composition (V %) Sample No. diesel n-butanol 2-butanol iso-butanol t-butanol 21 100 0 0 0 0 22 90 10 0 0 0 23 90 0 10 0 0 24 90 0 0 10 0 25 90 0 0 0 10 26 90 0 5 0 5

TABLE 6 Test Results of Diesel-Butanols Cetane Heat of combustion Cloud pour point RVP Smoke point Sample No. Index (BTU/lb) point (C.) (F.) (psi) (mm) 21 55.04 19327 5.89 40 2.12 13 22 52.4 18927 5.06 40 0.38 14 23 51.43 18961 4.61 40 0.61 13 24 49.11 18992 5.67 45 1.09 14 25 49.61 18971 5 40 1.13 14 26 48.68 18922 5.61 35 14

Runs 21-26 demonstrate that there are no significant negative effects (cloud point, smoke point, BTU) introduced when mixed butanols are added to the diesel at 10% level. Both Cetane and RVP are slightly reduced.

Experiments demonstrated that neat mixed butanols provided a stand-alone octane (RON) above 100. As indicated previously, the blending characteristics of the mixed butanols are not linear and therefore are not predictable.

While the invention has been shown or described in only some of its embodiments, it should be apparent to those skilled in the art that it is not so limited, but is susceptible to various changes without departing from the scope of the invention.

Those skilled in the art will recognize that many changes and modifications can be made to the method of practicing the invention without departing from the scope of the present invention. In the specification, there have been disclosed embodiments of the invention and, although specific terms are employed, they are used in a generic and descriptive sense only and not for the purpose of limitation, the scope of the invention being set forth in the following claims. The invention has been described in considerable detail with specific reference to these illustrated embodiments. It will be apparent, however, that various modifications and changes can be made within the spirit and scope of the invention as described in the foregoing specification. Furthermore, language referring to order, such as first and second, should be understood in an exemplary sense and not in a limiting sense. For example, it may be recognized by those skilled in the art that certain steps can be combined into a single step. 

1. A fuel composition having performance properties comparable to ethanol-based or MTBE blended fuels, the fuel composition comprising: a. a fuel component, the fuel component being present in an amount sufficient to provide adequate BTU content for use in combustion or compression engines; and b. a fuel additive comprising at least two butanols, the fuel additive being present in an amount sufficient to improve an octane rating for the fuel composition, in an absence of methanol, ethanol, or MTBE.
 2. The fuel composition of claim 1 wherein the butanol comprises 2-butanol, iso-butanol, tert-butanol, or combinations thereof.
 3. The fuel composition of claim 1, wherein the butanol excludes n-butanol.
 4. The fuel composition of claim 2 wherein the butanol comprises a mixture of 2-butanol and tert-butanol, the ratio of 2-butanol and tert-butanol being present in a range of about 5:95 vol. % to about 95:5 vol. %.
 5. The fuel composition of claim 1 having RON values ranging from about 85 to about
 110. 6. The fuel composition of claim 1 having BTU values ranging from about 105,000 BTU/gallon to about 120,000 BTU/gallon.
 7. The fuel composition of claim 1 having a RVP ranging from about 0.2 psi to about 20 psi.
 8. The fuel composition of claim 1 having MON values ranging from about 75 to about
 100. 9. The fuel composition of claim 1 having cetane index values ranging from about 40 to about
 60. 10. The fuel composition of claim 1, wherein the fuel component comprises gasoline, diesel, jet fuel, aviation gasoline, heating oil, bunker oil, or combinations thereof.
 11. The fuel composition of claim 1, wherein the fuel component is present in a range of about 40 vol. % to about 99 vol. % and the fuel additive is present in a range of about 1 vol. % to about 60 vol. %.
 12. A neat fuel composition that is environmentally friendly and has comparable performance properties to ethanol-based or MTBE-based fuels, the neat fuel composition consisting essentially of a mixed butanol fuel having an octane rating suitable for use in combustion or compression engines.
 13. The neat fuel composition of claim 12 wherein the mixed butanol fuel comprises 2-butanol, iso-butanol, tert-butanol, or combinations thereof.
 14. The fuel composition of claim 12 wherein the mixed butanol fuel consists essentially of 2-butanol, iso-butanol, tert-butanol, or combinations thereof.
 15. The neat fuel composition of claim 13 wherein the mixed butanol fuel comprises 2-butanol and tert-butanol, the ratio of 2-butanol and tert-butanol in a range of about 5:95 vol. % to about 95:5 vol. %.
 16. The neat fuel composition of claim 12 having RON values ranging from between about 85 and about
 110. 17. A method of preparing a fuel composition for use in combustion or compression engines, the method comprising the step of: combining a mixed butanol composition with a fuel component, the mixed butanol composition consisting essentially of 2-butanol, iso-butanol, tert-butanol, or combinations thereof and being present in an amount sufficient to improve an octane rating for the fuel composition, the fuel component comprising gasoline, diesel, jet fuel, aviation gasoline, heating oil, bunker oil, or combinations thereof, and the fuel component being present in an amount sufficient to provide adequate BTU content for use in combustion or compression engines.
 18. The method of claim 17, wherein the fuel component is present in a range of about 40 vol. % to about 99 vol. % and the fuel additive is present in a range of about 1 vol. % to about 60 vol. %. 